In an unusually stark warning, Japan’s prime minister during last year’s nuclear crisis told a parliamentary inquiry on Monday that the country should discard nuclear power as too dangerous, saying the Fukushima accident had pushed Japan to the brink of “national collapse.”

In testimony to a panel investigating the government’s handling of the nuclear disaster, the former prime minister, Naoto Kan, also warned that the politically powerful nuclear industry was trying to push Japan back toward nuclear power despite “showing no remorse” for the accident. ...

In his testimony, Mr. Kan said that Japan’s plant safety was inadequate because energy policy had been hijacked by the “nuclear village” — a term for the power companies and pronuclear regulators and researchers that worked closely together to promote the industry. He said the only way to break their grip was to form a new regulatory agency staffed with true outsiders, like American and European experts.

“Gorbachev said in his memoirs that the Chernobyl accident exposed the sicknesses of the Soviet system,” Mr. Kan said, referring to the 1986 explosion of a reactor in Ukraine, which spewed radiation across a wide swath of Europe. “The Fukushima accident did the same for Japan.” ...

He complained that nuclear regulators and the plant’s operator, Tokyo Electric Power, or Tepco, kept him in the dark about crucial details in the days immediately after a huge earthquake and tsunami on March 11, 2011, knocked out cooling systems at the Fukushima Daiichi plant, causing three of the plant’s reactors to melt down.

He said he tried to be fully open with the public and hid nothing. But he seemed to undermine that claim when he disclosed that in the early days of the crisis he feared it could spiral out of control, even as his own ministers were giving public reassurances that they had the plant under control.

He said he feared additional meltdowns could “release into the air and sea many times, no, many dozens of times, many hundreds of times the radiation released by Chernobyl.”

Those fears led to the most extraordinary moment of the crisis, when Mr. Kan walked into Tepco’s headquarters after being told the company wanted to evacuate its staff from the crippled plant. He demanded that they stay, saying he was prepared to put his own life on the line to prevent the disaster from worsening.

He also defended his visit to the plant on the day after the earthquake, which has been widely criticized for distracting plant personnel at a crucial juncture in their efforts to save the overheating reactors. Mr. Kan told the panel that he wanted to get an assessment directly from the plant manager because he felt Tepco officials in Tokyo were not giving him enough information.

But his strongest comments came at the end of his testimony, when a panel member asked if he had any advice for the current prime minister. Mr. Kan replied that the accident had brought Japan to the brink of evacuating metropolitan Tokyo and its 30 million residents, and that the loss of the capital would have paralyzed the national government, leading to “a collapse of the nation’s ability to function.”

He said the prospect of losing Tokyo made him realize that nuclear power was just too risky, that the consequences of an accident too large for Japan to accept.

“It is impossible to ensure safety sufficiently to prevent the risk of a national collapse,” Mr. Kan said. “Experiencing the accident convinced me that the best way to make nuclear plants safe is not to rely on them, but rather to get rid of them.”